Mechanistic Aspects of deNOx Processing over TiO2 Supported Co鈥揗n Oxide Catalysts: Structure鈥揂ctivity Relationships and In Situ DRIFTs Analysis

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• 作者：Hang Hu ; Sixiang Cai ; Hongrui Li ; Lei Huang ; Liyi Shi ; Dengsong Zhang
• 刊名：ACS Catalysis
• 出版年：2015
• 出版时间：October 2, 2015
• 年：2015
• 卷：5
• 期：10
• 页码：6069-6077
• 全文大小：686K
• ISSN：2155-5435

文摘

Anatase TiO₂-supported manganese and cobalt oxide catalysts with different Co/Mn molar ratios were synthesized by a conventional impregnation method and used for selective catalytic reduction (SCR) of NO_x with NH₃. The catalysts were characterized by N₂ adsorption/desorption, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed desorption with NH₃ and NO_x. Characterization of the catalyst confirmed that by using Co₃O₄ over Mn/TiO₂, we enhanced NO oxidation ability. From in situ diffuse reflectance infrared transform spectroscopy (DRIFTs) analysis of desorption and the transient reaction, we concluded that the addition of Co could remarkably lower the activation energy of NO_x chemisorption on the catalyst surface. In addition, low-temperature SCR activity mainly results from a 鈥渇ast SCR鈥?reaction. We observed four NO_x species (bidentate nitrates, gaseous NO₂, linear nitrites, and monodentate nitrites) on the surface of Mn/TiO₂ and Co鈥揗n/TiO₂ catalysts that all participated in the SCR reaction in the high temperature range. Doping of cobalt greatly improved the reactivity of gaseous NO₂, linear nitrites, and monodentate nitrites, which makes Co鈥揗n/TiO₂ a highly effective NH₃鈥揝CR catalyst.